I am playing a blu ray disc in sony blu ray. Whe I select audio for English (DTS HD Master Audio 5.1 Channel), I am only getting PCM 2.0 in the Bose but when I select audio from other language (which are in Dolby DIgital 5.1) I am getting Dolby Digital 5.1 in the Bose.

Please let me know how I can get 5.1 sound from DTS HD Master Audio 5.1 selection which is the only option for English language.

First off, S/PDIF transmission -- over either optical TOSLINK or coax -- does not have the bandwidth to carry Dolby TrueHD or DTS-HD MA signals. If you connect your Blu-ray player to your receiver with optical or coax, the audio will "fall back" to Dolby Digital, DTS or two-channel PCM (lossless, but only two channels).